Wireless communication equipment is here meant to be understood as a type of equipment arranged to establish radio communications with a radio communication network, and notably the mobile phones and the personal digital assistants (PDAs) or laptops that are provided with a radio communication device. These pieces of equipment are often named mobile station (MS) or user equipment (UE).
Nowadays more and more communication standards coexist or are about to coexist in a same network or in networks that are connected to one another. Among these standards may notably be cited the 2 G standard (such as GSM), the 2.5 G standard (such as GPRS), the 2.75 G standard (such as EDGE), and the 3 G standard (such as UMTS).
The transition from one standard to another may be an “easy” task when equivalent technologies are concerned. This is notably the case of the transition from the 2 G standard to the 2.5 G standard. These standards effectively use a same type of modulation (GMSK) so that the transition mainly requires to update the base stations (of the radio access network) with a new software release.
But when a new standard uses either a new modulation (such as the 8 PSK in case of EDGE) or a new radio access mode (as it is the case in UMTS), the transition is much more complex and costly. For instance the transition from GPRS to EDGE requires to update the base stations (BTSs) and the base station controllers (BSCs) of the radio access network both with new software and hardware releases. Therefore, the update of a whole network can take several years during which the cells which are associated with a GPRS base station will not be able to offer the radio access to the network services (for instance high throughput or high data bit rate) which is offered by the cells associated with an EDGE base station to the pieces of wireless communication equipment connected to them. The transition from GPRS or EDGE to UMTS is still more complex because it requires a new network deployment.
This situation penalizes the users of pieces of wireless communication equipment which offer a multimode working such as GSM/GPRS/EDGE modes or even GSM/GPRS/EDGE/UMTS modes (through two radio communication sub-systems).
Effectively, as is known by the man skilled in the art, a piece of wireless communication equipment is arranged to select the cell through which it accesses a network depending on the level of a radio parameter of the downlink signals (generally the BCCH carrier) it receives from the surrounding cells. In other words, a piece of wireless communication equipment selects the cell which momentarily offers the highest radio parameter level in order to reliably decode downlink signals and have the highest probability of uplink communication. Therefore, an EDGE or UMTS cell may be “hidden” by a GPRS cell which momentarily offers a better radio parameter level, thus forbidding equipment users to access the EDGE or UMTS network services.
So, the object of this invention is to improve the situation.